摘要
以变频改造后的某台轴流引风机上发生的轴系损坏故障现象为例,建立了风机在矢量变频模式下运行时轴系机电耦合扭振动力学模型,研究了升速过程中传动轴角速度和扭矩变化情况,分析了扭矩脉动情况下的频谱特性,并开展了扭矩和扭振现场测试。研究结果表明,三相交流电经过变频器调制输出到电机的信号中含有大量谐波,风机变频运行在一定转速范围时,电机输出扭矩中的谐波分量与轴系扭转固有频率重合,就会导致传动轴出现扭转共振,有可能出现较大幅度的扭矩脉动。转速较高时,也有可能出现因机电耦合所引发的扭振失稳现象。因电机和风机的转动惯量相差很大,脉动情况下联轴器两侧扭振幅度差别较大,导致联轴器所承受的脉动扭矩较大,容易引发联轴器损坏和转轴裂纹,对设备安全运行产生很大影响。设备变频改造时,应对轴系扭转振动特性和强度进行分析和评估。
The shaft torsional vibration model of an axial flow fan with variable frequency drive(VFD)was set up for the analysis of shaft break fault.The mechanical/electrical interaction effect of the fan with the vector convertor speed governing technique was considered.The variation of the driven shaft instant angular speed and torque during a run up process was simulated.The pulsation torque spectrum was given.The torsional vibration and the pulsation torque were measured in the field.It is shown that abundant harmonic components exist in the three phase signals output from the frequency converter.The harmonic components may coincide with the shaft torsional natural frequency in certain speed zone,which causes large torsional vibration and torque pulsation.In the high rotating speed zone,the self-excited torsional vibration caused by the mechanical/electrical interaction effect may occur.The torsional amplitude of the shaft sections beside the both ends of the coupling is different due to the difference between the moments of inertia of the fan and motor.It causes high torque pulsation on the coupling and therefore the break of the shaft and coupling,which is of great influence on the safe and reliable operation of the fan.So,the torsional dynamics and shaft strength should be analyzed before the VFD modification.
作者
张楚
张礼亮
刘石
高庆水
邓小文
杨毅
杨建刚
ZHANG Chu;ZHANG Liliang;LIU Shi;GAO Qingshui;DENG Xiaowen;YANG Yi;YANG Jiangang(Electric Power Research Institute, Guangdong Power Grid Co. , Ltd. , Guangzhou 510080, China;National Engineering Research Center of Turbo Generator Vibration, Southeast University, Nanjing 210096, China)
出处
《振动与冲击》
EI
CSCD
北大核心
2018年第6期168-173,共6页
Journal of Vibration and Shock
关键词
变频调速
引风机
扭振
机电耦合
variable-frequency drive
draft fan
torsional vibration
electromechanical coupling
