Experimental Study On The Correlation Of Vibration Characteristics Between Rotor And Tower Under Yaw

Under natural conditions,due to the influence of wind speed gradient,topography and other factors,the wind turbine is always in yaw operation state.yaw excitation force will induce bad vibration and fatigue damage of rotor.since the wind turbine is a rigid-flexible coupling multi-body system,the rotation of rotor will induce tower vibration.the tower will be affected by wind load,unit weight and other factors too.In the process of direct monitoring of the dynamic characteristics of the wind wheel,the wind turbine is easy to throw out the sensors of laid on the blades and winding the connecting wires with the sensors.In the wind turbine industry,it is difficult to monitor the dynamic characteristics of the rotating wind turbine structure in real time and directly.Based on this,in order to study the correlation between the vibration characteristics of rotor and the tower under yaw,consider whether the appropriate vibration acceleration sensor can be arranged on the tower of the small horizontal axis wind turbine,and realize indirect monitoring of the dynamic characteristics of the rotor structure by analyzing its vibration signal.The dynamic strain signals of blades and vibration signals of tower under yaw condition are collected synchronously by means of rotating telemetry stress and strain wireless testing equipment and PLUSE21.0 vibration testing and analysis system.The correlation between the vibration characteristics of rotor and tower under yaw condition is studied experimentally,and the following conclusions are drawn.In the dynamic test,the correlation analysis of tower vibration signal and rotor dynamic strain signal under yaw is carried out by spectrum analysis method.It is found that there is a one-to-one relationship between the peak frequency of wind turbine tower vibration spectrum correlation order and the peak frequency of rotor strain spectrum.Under yaw condition,the rotation of rotor causes tower vibration.Through the analysis of vibration signals at the measured points of the tower,the results show that under the non-resonant condition,the vibration acceleration of the tower is greater than that of the axis at the fundamental frequency of the rotor rotation,and the vibration acceleration of the yaw state in the same direction is greater than that of the non-yaw state.when the resonance occurs at the disk effect frequency of rotor,the lateral vibration acceleration of the tower is greater than that of the non-yaw state.The dynamic acceleration value of the axial vibration of the tower is larger than that of the transverse vibration when resonance occurs at the first bending frequency of the tower,and with the occurrence of the yaw,the axial vibration acceleration of the tower decreases relatively,and the transverse vibration acceleration value increases relatively.Under yaw conditions,the influence of tower vibration on wind turbines is different under different working conditions.Through spectrum analysis of dynamic strain signal of wind turbine,the variation law of radial strain at the fundamental frequency of the rotorrotation under different conditions is obtained: under non-resonance condition,the radial strain at the same measuring point of wind turbine blade under larger yaw angle condition is generally larger than that under smaller yaw angle condition;when resonance occurs at the frequency of wind turbine disk effect,the radial strain at different yaw angle is compared.It is found that the radial strain values of each measuring point are larger at yaw angles of 10 and 25 and the radial strain values of rotor are larger when resonance occurs at the first bending frequency of the tower and larger yaw angles occur.In this paper,by means of experimental testing,the correlation between the vibration characteristics of rotor and tower under yaw is studied experimentally.At the same time,from the point of view of indirect monitoring,a new method of arranging vibration acceleration sensors on the tower to diagnose the dynamic characteristics of wind turbine blades under yaw condition is explored,which has certain guiding significance in engineering application.