A Study On The Direct-drive Permanent Magnet Wind Turbine System With Wide Speed Operation And Multiple Branch

With the development of wind power technology,wind power system is developing to high efficiency and large capacity.For direct-drive permanent magnet wind power system,the narrower-range voltage of the power converter directly limits the turbine speed range,and then affect the turbine efficiency in low speed wind.At the same time,the power converter capacity directly limits the capacity of power system.In order to solve the above problems,this paper proposes a novel cascaded multi-dcbranch direct-drive permanent magnet wind power system topology.The direct-drive generator adopts isolated multi-branch winding structure,which can reduce the current level of each branch,enhance the generator branch fault tolerance and be beneficial to the expansion of the generator capacity.The cascade of multi-dc-branch can be controlled to ensure that the bus voltage fluctuates in a narrow range.In this way,the efficiency of the wind turbine can be improved in low wind speed.In this paper,multi-branch direct drive permanent generator and finite element model is designed.By adopting the single wizard connectivity of diode and high fault tolerance of tree topology,a novel cascaded multi-dc-branch topology is designed,with less switching devices,low cost,high fault tolerance.The relation of generator speed range is deduced,and the constraint condition with continuous speed range is analyzed.The simulation model is built by using matlab/simulink software to verify the feasibility the novel cascaded topology.Through the experiment,the speed expansion performance with the novel cascaded topology is further verified.