| With the increasing in the installed capacity of the single wind turbine,the height of the wind turbine tower has reached to 100 ～ 200 meters compared with the initial 30 meters,therefore,higher requirements are put forward for the strength,stiffness and stability of wind turbine tower structure thereafter.This thesis proposed a new triangular section wind turbine tower structure,of which the structural form is deeply studied in the meantime.In addition,the yaw brake is the structure to control the rotation of wind turbine,which is an important part of wind power generation system.In this thesis,some mechanical problems in the structure of wind turbine yaw brake are deeply studied.However,there is a common problem to be solved in both of the triangular section tower structure and the yaw brake structure of wind turbine: the antiloosening of structural bolts,so it is necessary to carry out relevant experiments on how to prevent loosening of structural bolt.In the study of triangular section wind turbine tower structure: 1)The wind load borne by triangular section wind turbine tower is studied,the influence of tower top concentrated mass on tower wind load calculation is analyzed,the wind load of each floor of triangular section wind turbine tower is determined through calculation,and the material selection of triangular section wind turbine tower is also studied;2)For the given wind turbine model,the reasonable size of the main material and inclined material of the triangular section wind turbine tower and the reasonable design scheme of the overall structure are analyzed and calculated,in addition,five design schemes of the triangular section wind turbine tower structure are proposed.According to the comprehensive analysis and comparison,scheme 5 is selected as the recommended design scheme,of which the triangular section wind turbine tower structure is further analyzed and calculated by finite element method,and then the internal forces of main materials and inclined materials of the tower are obtained;3)The triangular section tower and the cylindrical tower are comprehensively compared and analyzed from the aspects of steel consumption,shear stress strength,torque action,torsional instability resistance,strength of the tower under bending moment,bending instability resistance and seismic load resistance.It is concluded that the triangular section tower has more advantages than the cylindrical tower.Through the above three aspects of research,the conclusions provide a basis for the engineering application of triangular section wind turbine tower structure.In the study on the structure of wind turbine yaw brake: 1)The mechanical model of the disc yaw brake is analyzed;The force distribution of the brake under external load is studied,and the relative slip possibilities between the engine room and the upper tong body,the upper tong body and the lower tong body are checking calculated;2)The finite element calculation of the disc yaw brake is carried out to check whether connecting parts and bolts of the wind turbine yaw brake can meet the strength requirements under the limit load condition.In summary,the theoretical analysis and the finite element calculation of the wind turbine yaw brake provide a reliable basis for the structural design and optimization of the yaw brake and the engineering application of the brake.The bolts are widely used as fasteners in triangular section tower and yaw brake on wind turbine in the wind power generation system,while shaking and vibration are commonly happened in the process of power generation,which is very unfavorable to the connection of bolts.In addition,the maintenance of connecting bolts in the triangular section wind tower structure and yaw brake structure on wind turbine is very inconvenient.Consequently,as a very important fastener in wind power generation system,the bolts once become loose,the consequences will be unimaginable.Therefore,this thesis has carried out the following three aspects of experimental studies on the anti-loosening of connecting bolts: 1)Inventing a new type of anti-loosening nut by doing some short processing on the ordinary nuts.Through the test,it is verified that the anti-loosening performance of the bolt equipped with the new type is better than most of those equipped with the ordinary ones;2)Designing a new type of antiloosening washer and anti-loosening nut,on which the anti-loosening performance is experimentally studied to verify that its anti-loosening performance meets the design requirements;3)Inventing a set of bolt anti-loosening monitoring device,which can monitor whether the bolt is loose in real time,and the monitoring of bolt looseness has achieved the expected effect.Through theoretical analysis and finite element calculation,the structural form of triangular section wind turbine tower is determined,and the triangular section wind turbine tower and the cylindrical tower are comprehensively compared and analyzed;It also checked whether connecting parts and bolts of the wind turbine yaw brake can meet the strength requirements under the limit load condition;Finally,the relevant experiments on how to prevent loosening of bolt is carried out.The research conclusions provide a reliable basis for the engineering application of triangular section tower and yaw brake on wind turbine. |
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