Study On Hydraulic Drive And Pitching System Of Horizontal Axis Tidal Current Turbine

Tidal current turbine has to be set underwater during its operation.The motor need to be assembled in the chamber of the turbine because of the traditional gearbox powertrain.So many seals including dynamic seals and static seals once leaked,the costly motor is broken.Besides,traditional mechanical powertrain is rigid transmission which may give motor an abrupt torque attack and meanwhile,it is hard to control the motor speed.Focus on these,the article present the hydraulic system powertrain for its superiority in flexible transmission and easier control of motor speed.Furthermore,the motor being set overwater can lower the risk raised by the seals.Pitching technology plays an important role in the steadily and safety operation of horizontal tidal current turbine,so a study on a bevel gears pitching system mechanism based on electro-hydraulic proportional speed control was carried on in some level.This thesis includes seven chapters.Chapter one briefly presents the background of tidal current turbine and summarizes the current situation both in China and abroad.Chapter two presents the basic theories,blade element theory and actuator disk theory of horizontal axis tidal current turbine.Besides,the hydraulic system schematic diagram and control strategy are also introduced here.Chapter three presents the rough layout scheme,body structure,bevel gear pitching mechanism,pitching angle measurement mechanism of hydraulic drive horizontal axis tidal current turbine.And through simulation analysis of the structure,this chapter raised a prioritization scheme for its better performance.Chapter four presents the design details of hydraulic system such as the choice of elements and the design of the pipes.Chapter five firstly presents the simulation study on an inner curve radial piston pump and its volumetric efficiency is fully analyzed and then it presents the AMESim-MATLAB/Simulink analysis of the whole tidal current turbine in both higher and lower tidal speed through the mathematical model of the turbine,the hydraulic system,the electric motor and the electric network built in the both software.Chapter six presents a measurement mechanism of volumetric efficiency of the hydraulic motor which was used as a hydraulic pump.Chapter seven makes the conclusion and gives study work of the next step.