Wind Turbine Gear Transmission Research Articles

Design optimization of a wind turbine gear transmission based on fatigue reliability sensitivity

Fatigue failure of gear transmission is one of the key factors that restrict the performance and service life of wind turbines. One of the major concerns in gear transmission under random loading conditions is the disregard of dynamic fatigue reliability in conventional design methods. Various issues, such as overweight structure or insufficient fatigue reliability, require continuous improvements in the reliability-based design optimization (RBDO) methodology. In this work, a novel gear transmission optimization model based on dynamic fatigue reliability sensitivity is developed to predict the optimal structural parameters of a wind turbine gear transmission. In the model, the dynamic fatigue reliability of the gear transmission is evaluated based on stress-strength interference theory. Design variables are determined based on the reliability sensitivity and correlation coefficient of the initial design parameters. The optimal structural parameters with the minimum volume are identified using the genetic algorithm in consideration of the dynamic fatigue reliability constraints. Comparison of the initial and optimized structures shows that the volume decreases by 3.58% while ensuring fatigue reliability. This work provides new insights into the RBDO of transmission systems from the perspective of reliability sensitivity.

On-Line Fault Detection in Wind Turbine Transmission System using Adaptive Filter and Robust Statistical Features

To reduce the maintenance cost, avoid catastrophic failure, and improve the wind transmission system reliability, online condition monitoring system is important. Developing effective online fault detection methodology is important. In this paper, an adaptive filtering technique is applied for enhancing the fault impulse signals-to-noise ratio in wind turbine gear transmission systems. Multiple statistical features designed to quantify the impulse signals of the processed signal are extracted for rotating machine fault detection. The multiple dimensional features are then transformed into one dimensional feature. A minimum error rate classifier will be designed based on the transformed one dimensional feature to identify the gear transmission system with defect. Vibration signals collected from wind turbines in the real operation will be used to demonstrate the effectiveness of the presented methodology.

Load characteristic analysis and fatigue reliability prediction of wind turbine gear transmission system

Wind energy is the inexhaustible renewable energy source, and the number of wind power utilization in many countries is also growing rapidly. Wind turbine works in harsh natural environment, and long-term random wind load will cause tremendous damage on the internal gear transmission system. In order to accurately predict the fatigue reliability for a 5 MW large-scale wind power gear transmission system in service, a detailed system simulation model is established, and the accurate stress calculation is carried out for the contact fatigue failure mode on tooth surface. In this paper, the linear relationship between the input torque of gear system and the maximum contact stress of each gear is established, and the load history conversion between the input torque and the contact stress can be realized. Then the Miner cumulative damage theory is used to transform the complex random stress history into equivalent constant amplitude cyclic stress, which is load input variable for the reliability prediction model. At the same time, a contact fatigue test for tooth surface is carried out, and P-S-N curves of the gear samples with specific parameters are obtained, which is the strength input variable for the reliability prediction model. In order to reflect the uncertainty effect of service load on the reliability of gear transmission system, the randomness of load history is expressed complementarily at macro level and micro level, respectively. The traditional stress and strength interference theory is extended, and the reliability model of series system considering the statistical dependence among part failures is established. Finally, the advantage of the proposed model is demonstrated by comparing the prediction result of the new model with that of the traditional model.

Probabilistic design optimization of wind turbine gear transmission system based on dynamic reliability

In this paper, a probabilistic design optimization method for wind power gear drive system has been put forward based on the dynamic reliability. A pure torsional dynamic model of 1.5 MW wind turbine gear transmission system is developed which is based on lumped parameter method with incorporation of gear meshing stiffness and transmission error. By taking the wind load and the gear parameters as random variables, the variation in dynamic reliability of the system with time is obtained. The probabilistic optimization design model of the wind turbine gear transmission system with minimum displacement and volume is built. The parameters affecting the dynamic performance and reliability are taken as optimization design variables. The system reliability, the effects of random parameters on the reliability, the normal meshing condition and gear strength are taken as constraint conditions. We choose the gear transmission system of a 1.5 MW wind turbine for the system optimization and experimental verification. The results show that the system optimization based on dynamic reliability can reduce the volume of the system by 17.94 % and the system reliability is also guaranteed. Moreover, the vibration of each component of the system is reduced which is beneficial for smooth operation of the gear transmission system of wind turbine.

An Approximate Solution Method of Dynamic Reliability for Wind Turbine Gear Transmission with Parameters of Uncertain Distribution Type

The reliability evaluation of wind turbine system is the theoretical basis for engineering design, and how to deal with its complex wind loads is the technical challenge for it. Considering the distribution type of wind loads is uncertain, the stress-strength interference model based on the assumption of normal distribution can’t be applied to the reliability of wind turbine gear transmission. For this, the dynamic reliability model for wind turbine transmission with uncertain distribution parameters is established firstly with the deterioration of gear contact stress and strength degradation being considered. Then, the dynamic reliability is solved by approximate expansion of the model function into standard normal distribution function based on the stochastic perturbation theory and the Edgeworth series method. In the absence of experimental data, the first four moments of the random parameters with uncertain distribution are obtained by Monte Carlo method. Meanwhile, the dynamic reliability sensitivity to gear parameters is derived by the same method and the sensitivity variation is given which effectively reflecting the influence of gear parameter changes on the system reliability of wind power gear drive, and providing an accurate theoretical basis for the optimal design of the project.

Coupled Dynamic Characteristics of Wind Turbine Gearbox Driven by Ring Gear Considering Gravity

Gravity is usually neglected in the dynamic modeling and analysis of the transmission system, especially in some relatively lightweight equipment. The weight of wind turbine gearbox is up to tens of tons or even hundreds of tons, and the effects of gravity have not been explored and quantified. In order to obtain accurate vibration response predictions to understand the coupled dynamic characteristics of the wind turbine gear transmission system, a comprehensive, fully coupled, dynamic model is established by the node finite element method with gravity considered. Both time-domain and frequency-domain dynamic responses are calculated using the precise integration method with various excitations being taken into account. The results indicate that gravity has a significant impact on the vibration equilibrium position of central floating components, but the changing trends are different. Gravity does not change the composition of the excitation frequency, but will have a certain impact on the distribution ratio of the frequency components. And the high frequency vibrations are hardly affected by gravity. In addition, the load sharing coefficient is greater when gravity is taken into account, both of internal gearing and of external gearing system. When the planet gears have a certain position error in accordance with certain rules, the load sharing performance of the system will be better.

Dynamic characteristics of wind turbine gear transmission system with random wind and the effect of random backlash on system stability

In order to study the dynamic characteristics of gear transmission system of wind turbine with random wind and the effect of random backlash on system stability, a stochastic volatility model is established to obtain the external excitation of gear transmission system of wind turbine. A dynamic model of system is set up with the consideration of gear time-varying mesh stiffness, transmission error and backlash. The dynamic behavior of system with random wind and the effect of random backlash on system stability are obtained using numerical method. The results show that: (1) The vibration displacement of system components has the similar trends with external excitation, and the higher the speed, the greater the vibration displacement. (2) Random backlash has a significantly influence on system stability. The instability of system decreases at first and then increases with the increase of mean backlash, and the stability of system decrease with the increase of standard deviation of backlash. The operation stability of a wind turbine will improve if select an appropriate gear backlash.

Dynamic Reliability Analysis of Gear Transmission System of Wind Turbine in Consideration of Randomness of Loadings and Parameters

A dynamic model of gear transmission system of wind turbine is built with consideration of randomness of loads and parameters. The dynamic response of the system is obtained using the theory of random sampling and the Runge-Kutta method. According to rain flow counting principle, the dynamic meshing forces are converted into a series of luffing fatigue load spectra. The amplitude and frequency of the equivalent stress are obtained using equivalent method of Geber quadratic curve. Moreover, the dynamic reliability model of components and system is built according to the theory of probability of cumulative fatigue damage. The system reliability with the random variation of parameters is calculated and the influence of random parameters on dynamic reliability of components is analyzed. In the end, the results of the proposed method are compared with that of Monte Carlo method. This paper can be instrumental in the design of wind turbine gear transmission system with more advantageous dynamic reliability.

Parameter Optimization Design and Stress Analysis of ANSYS in Inclined Gear Transmission System of Wind-Turbine

ncreasing speed Gear-box is one of the most important components of wind-turbine. Gear design directly affect the operating life and reliability of gear-box. Based on the 1.5MW wind-turbine as the research object in this paper, we optimized the design parameters of Inclined gears, analysed its bending stress reliability, further verified the gear maximum stress and stress position, to provide a scientific reference for making Inclined gears later.

Optimization Design of MW-Class Wind Turbine Gear Transmission System Based on MATLAB and SQP Algorithm

This paper introduces the principle of the SQP algorithm and how to realize in MATLAB optimization toolbox. With mega watt wind turbine gear transmission system as the research object, the selection of the appropriate design variables and constraints, as the volume of transmission system is the smallest and part of the gear rotational inertia minimum for target function, and set up the optimization mathematical model. Use the MATLAB optimization toolbox to optimize, and then calculate and analysis the example. The results show that before and after the optimization of the system, the volume and the rotational inertia of the gear are significantly reduced. This paper will supply some references for the wind power gear transmission system design.