Reliability Analysis Of 2.5 MW Wind Turbine Gearbox

At present wind power is the most economically feasible and mature technology renewable clean energy in all kinds of new energy. The exploration and research of new energy technology allow no delay for the increasing energy and environment pressure with the rapid development of our country’s economics. Wind turbines can convert wind power into electrical energy. It includes turbine blades, gear box, generator and yaw controller and its key components are gear box, which can realize acceleration. The wind turbines should run for twenty years for its remote installation sites like marine and mountain which bring inconvenience maintenance and high costs. Meanwhile the great random wind load variation lead to the frequent gearbox malfunctions which climbed to 60 percent and this has severely impacted its steady and reliability. In this thesis, the main failure mode and failure cause are determined by failure models and effects analysis(FMEA) in a 2.5 megawatt(MW) wind turbine gearbox. The gear stress distribution are obtained by load duration distribution(LDD) in a experiment wind load and Romax Designer to get the correspondence model. Meanwhile the reliability of the gear is researched under dependence factors. The main contents are as follows:Firstly, the background and significance of the paper are described. The development status of the wind power and wind turbine gearbox are reviewed. Gear transmission system dynamics and the research of reliability are summarized and analysed. Then the main research contents are proposed.Secondly, construction, work principle and ambient working conditions of 2.5 MW wind turbine gearbox produced by a gearbox factory are analysed. FMEA are realized based on the failure instance of wind turbine gearbox in using and testing environment. Then the main failure model, pitting fault, gear scuffing, gear wearing, and gear fracture are determined and random wind load is one of the main reasons of the wind turbine gearbox.Thirdly, based on the many years monitoring data of experiment wind load, the LDD are determined with the Rain-flow Method. Then the characteristic and main function of Romax Designer are briefly reviewed. And the 2.5 MW wind turbine flexible multi-body model areobtained based on the software. Contact stress and bending stress are calculated by taking LDD into the flexible multi-body model. So the distribution of contact and bending stress are determined with statistic method which establishes the foundation for the subsequent fatigue-reliable computation.Fourthly, the characteristic and the comment Copula function are briefly viewed. Based on the function the gear fatigue contact calculation model are determined under the dependency between contact fatigue and bending fatigue with the use of stress-strength interference model and fatigue life curve(S-N). The gear fatigue reliability is calculated with residual square sum(RSS) and Copula function parameter estimated by optimized MATLAB toolbox.Finally, it summarizes the whole text and views the prospect of the wind turbine gearbox reliability.