600MW机组次同步振荡下轴系扭振校核及疲劳寿命损耗计算

Research on fatigue life expenditure and torsional vibration check of a 600MW unit under subsynchronous oscillation

针对某超临界600 MW机组在运行过程中经常出现的低振幅次同步振荡(SSO)问题,本文采用Riccati传递矩阵法建立了该机组的集中质量模型,求解了轴系的扭振固有频率,并与轴系的实测扭振固有频率进行了对比,证明了该模型计算结果与实测结果相符,可用于机组扭振分析。同时,应用本文模型,根据该机组轴系的扭振振型求解了轴系的扭振应力相对值,确定了SSO下轴系的危险截面;建立了次同步振荡下机头转速差与最危险截面疲劳寿命之间的关系,可对该机组发生低振幅SSO时的扭振安全性和疲劳寿命损耗进行评估。

Low-amplitude subsynchronous oscillation（SSO）problem occurred frequently during operation of a supercritical 600 MW unit.To solve this problem,the Riccati transfer matrix method was applied to establish lumped-mass model for this unit.The torsional vibration natural frequency of shafting was solved,and the result was compared with the actual measured torsional vibration natural frequency of shafting.It was proved that the calculation results agreed well with the actual measured results,this model could be used to analyze the torsional vibration of this unit.Moreover,the relative value of torsional vibration stress shafting was solved based on the torsional vibration mode of this unit shafting,and the dangerous section of shafting was determined under SSO.The relationship between speed difference of the unit head and the fatigue life of the most dangerous section under SSO was established,the torsional vibration safety and fatigue life expenditure of the unit when the low-amplitude SSO occurred were evaluated.It provides important references for the same type units to analyze SSO.