Research On The Control System For The Main Drive Of Wind Turbine With Hydra-Mechanical Transmission

With the development of human society,the demand of energy increases drastically,which results in fossil fuels gradually drying up and meanwhile causing lots of environmental problems.Therefore,the development and utilization of renewable energy is urgent.Wind power is the renewable energy technology with the most mature technology in new energy technologies.The wind is time-varying,so the torque bore by the transmission system in wind power system,such as the gears,is fluctuate largely and frequently.Therefore,the break-down time caused by transmission system is the longest and the mount of money spent on repairing it is also the largest.In recent years,wind turbine based on hydraulic transmission has been developed,but its transmission efficiency is low.In this paper,the control system of the main transmission in wind turbine based on mechanical-hydraulic hybrid transmission has been studied.Through the rational allocation of planetary gear train and reasonable control,most of the power captured by wind turbine is transmitted by mechanical transmission and the small and fluctuate part is transmitted by hydraulic transmission.And under the premise of realization of wind turbine power control,it can not only ensure the efficiency of the entire transmission system,but also can weaken the torque ripple of the transmission system.The paper is divided into five chapters to introduce the research on Mechanical hydraulic hybrid wind turbines main drive control system.The main contents of the five chapters can be summarized as follows:The first chapter introduces the research background,domestic and external development situation of wind power and technology status.Also the first chapter introduces the domestic and external development situation of hybrid wind turbine.The research content and research significance are proposed.The second chapter firstly analyzes mechanical hydraulic hybrid transmission principle,proving the feasibility of its application in wind turbines.And then the control strategies of existing wind turbines at various stages are studied.Combining the characteristics of the mechanical hydraulic hybrid wind turbines,the control strategies at different stages are made.The third chapter mainly studies on the simulation of mechanical hydraulic hybrid wind turbines.First of all,simulation models are established in the software AMESim and Matlab/Simulink.Through simulation we can conclude,under the premise of realization of wind turbine power control,this wind turbine can not only ensure the efficiency of the entire transmission system,but also can weaken the torque ripple of the transmission system.The fourth chapter mainly studies on the experiment of the mechanical hydraulic hybrid wind turbines.Main works includes hardware selection,design of PLC control program and Lab VIEW programming on up computer.Through test,we can conclude,under no-load condition through adjusting the displacement of the pump,the mechanical hydraulic hybrid transmission test bench can effectively maintain the generator speed stability at the rated speed;Under the condition of off-grid operation by adjusting the displacement of the pump the test bench can achieve generator constant frequency running;And the mechanical hydraulic hybrid drive system has a certain function of absorption torque ripple;Compared with pure mechanical transmission,the transmission efficiency of mechanical hydraulic hybrid transmission system does not decrease too much,and in fact it has a high transmission efficiency relatively.In the fifth chapter,the paper's research work and outcomes are generalized,and the directions for further working are also pointed out.