Numerical Simulation Of Wind Turbine Pitch Bearing

With the large-scale development of wind turbine capacity, for its high efficiencyand utility, variable pitch control have gradually replaced the fixed pitch control, to beused in a megawatt-class large-scale variable-speed wind turbine. As the finalimplementing part of variable pitch system, it is essential to keep the safe operation ofpitch bearing for the whole wind turbine normally controlling speed. In the workingcondition, a large contact stress is the main reason for pitch bearing failure of wear;while a large number of engineering practices show that, it is the other reason of thethermoplastic deformation due to frictional heat generation between the roller andraceway that causes the bearing wear. Through the establishment of the pitch bearingsimulation model in the numerical method, to analyze bearing strength and predict theimpact of the friction and heat in working condition, which is a worthy of work toensure success of the design, improve design efficiency and save the cost of test.The study contents are following:First, based on the theory of multi-body dynamics, a virtual prototype model of thewind turbine is made by multi-body dynamic simulation software ADAMS, and by thesimulation results, load of the pitch bearing is obtained for strength check in finiteelement analysis.Second, based on the above research, by the general finite element analysis(FEA)software ABAQUS, four-point contact pitch bearing finite element model is built forstrength check and a preliminary wear forecast.Last, based on the explicit dynamic theory, through the finite element modelestablishment of the pitch bearing frictional heat generation, the impact of the frictionalheat on the structural strength is analyzed by the numbers.The main conclusions are as follows:1. Results from the multi-body dynamics simulation show that: the load on pitchbearing is proportional to wind speed, which is changing over time in accordance with a periodic decay; besides, a mutation on the load will be created by the vibration of pitchblades.2. The FEA results of the pitch bearing strength check show that: it is best for thepitch bearing load-performance when the raceway contact angle is45o; as the racewaycontact angle decreasing, it is more prone to lead to large stress concentration in thecontact zone between roller and raceways.3. The simulation results of pitch bearing frictional heat generation model showthat: the heat caused on the contact surface mainly depends on the friction coefficientand the variable pitch speed of pitch bearing; the maximum value of stress anddeformation in the contact zone change along with temperature and time.This paper is based on the theory of multi-body dynamics and finite element, todevelop a practical numerical method for wind turbine dynamic modeling and the fanpitch bearing’s strength check and wear prediction; at the same time, it also lays theground to analyze the damage and failure forms of the fan pitch bearing.