Dynamic Characteristics Study Of Speed Increaser For The Wind-driven Generator On Finite Element Analysis

Speed increaseing gearbox is the most important mechanism in wind-driven generator, which takes charge of wind energy conversion and power transmission. So the dynamic performance of the transmission system has a direct influence on the performance of wind-driven generator. Because of the particularity of the working place and the surrounding environment, the wind-driven generator must work safely for a long time under the changing load. In such case, the transmission system has to present the characteristics of high reliability, high stability and high life. It is important to study the dynamic characteristics of the speed increase gearbox of wind-driven generator deeply. In this paper,3.0MW wind-driven generator will be taken as the objective to study. Concrete research work is as follows:(1) The Auto-Regressive (AR) model is used to simulate the random wind speed in the wind farm. The data and the time-history of the random wind speed are got by using MATLAB. The wind energy curve and the input power curve of the wind-driven generator can also be calculated relating to the time-varying wind speed data.(2) The random wind load is considered as the external excitation of the gear transmission system of the wind-driven generator gearbox. The relation between wind speed and actual input power of wind-driven generator gearbox is analyzed by studying the power adjustment. Then the function of both actual input speed and actual input torque are inferred. On this foundation, the random wind speed curve is changed into curves of actual input speed and torque of wind-driven generator gearbox transmission system.(3) The internal excitation of the3.0MW wind-driven generator speed increaser mechanism is studied. The dynamic finite element model of gear transmission system is also built according to the3D model. The internal excitations such as meshing stiffness excitation and meshing error excitation are studied. The curves are got by analyzing the mechanism of the internal excitations. After that, by combining the two internal excitation curves, the curve of the exciting force can be built.(4) The dynamic contact characteristics of all levels of the gear transmission system are studied by using ANSYS LS-DYNA explicit dynamics software. The change of equivalent stress distribution of gear along with time of the whole meshing process is calculated. The regularity of stress distribution is summarized. The output level gear pair is studied, and then compares the simulating motion condition to the real motion condition.(5) The modal analysis of gear transmission system and the box are performed by means of finite element analysis software. The natural frequency and vibration model data of system is got. The modal analysis is carried out to combine its results with the input power density spectrum to execute random vibration analysis. It calculates the stress distribution and the deformation distribution. The dynamic response spectrum of some special points of the gearbox is also calculated. Then this paper analyzes the dynamic response of the gearbox under the random load. The modification is proposed according to the study.