Reliability Evaluation And Dynamic Characteristics Study Of Variable Speed Wind Generator Transmission System Under Varying Wind Load

Wind energy is a clean and non-pollution new energy, exploiting wind energy properly can solve the increasing energy and environmental problems. Because of high power and low vibration, the variable speed wind generator has been the main developing generator type of high-power wind generator in the future. The blade rotation speed of high-power wind generator is usually very low, so we should place a increasing-speed gear box between blade and generator in order to gain the speed for generating electricity. The gear box transmission system is a key part of wind generator, its reliability and dynamics level both directly decide the correct operation of wind generator. Because of the bad working environment, complex time-varying wind load and high erection, the gear transmission system of variable speed wind generator must have a high reliability and good dynamic characteristics. So, it is necessary to study on the reliability and dynamic characteristics of variable speed generator transmission system under varying wind load.The thesis is supported by National Natural Science Foundation, it investigated the reliability evaluation and dynamic performance of the 2MW wind generator transmission system. This paper mainly did following works:①A random wind model basing on the two parameters Weibull distribution is built. According to the average value and variance of wind speed, the shape parameter and scale parameter of Weibull distribution is estimated, the random wind model is built and the nature varying wind is simulated.②Realistic time-varying input torque and speed of variable speed wind generator gear box is got. The varying wind speed which is got from the random wind model is used to be the external excitation of gear transmission system. The relation between wind speed and realistic input power of variable speed wind generator gear box is analyzed; the function of input torque and wind speed and the function of input speed and wind speed are both got according to inference. On this foundation, the wind speed is changed into the input torque and speed of variable speed wind generator gear box.③Reliability evaluation of gear box transmission system is done. The main gear failure types are analyzed, the reliability of gear transmission system is got, and the reliability evaluation of gear system is done.④Dynamic model of gear transmission system is built. Considering the internal excitations such as the time-varying meshing stiffness, bearing stiffness and the meshing error, a dynamic model is built by using lumped-parameter method.⑤Dynamic characteristics of gear transmission system are studied. The vibration speed, displacement of gears and mesh force of each gear pair of the variable speed wind generator transmission system which is under the interaction of time-varying input torque and internal excitations are got by using Matlab, and the dynamic characteristics of gear transmission system under varying wind load are studied. The research results provide some references for design and analysis of the variable speed wind generator gear box.