增量传递矩阵法及其在轴系弯扭耦合振动中的应用

Increment transfer matrix method and its application in the coupled flexural and torsional vibrations analysis

将逐步积分法的思想与传统矩阵法相结合,提出了增量传递矩阵方法,使之能求解具有非线性力系统动力响应。基于多段集中质量模型和增量传递矩阵法,并结合R iccati法,建立了汽轮发电机组轴系弯扭耦合振动瞬态响应求解模型。利用该方法,针对某200 MW汽轮发电机组三相短路重合闸故障,进行了机组弯扭耦合振动响应特性研究,分析表明:弯振和扭振幅值变化与电网短路及重合闸时刻紧密相关,重合闸所带来的冲击比电网短路时刻更大;故障主要激发出扭振的前三阶固有频率来,弯振除工频主分量外,前几阶固有频率也被激发出来。在短路后至重合闸前的这一时间段内,扭矩主要含有工频及各阶固有频率成分,而在重合闸后的时间段内,扭矩各阶固有频率成分仍存在,但工频成分消失。

Based on step-by-step integration method and traditional transfer matrix method, an increment transfer matrix method is put forward, which can be directly used to analyze nonlinear differential equations. The combination of this method and Riccati method is employed in a multi-mass model, and the matrix equations for calculating the responses of coupled flexural and torsional vibrations are deduced. The responses properties of coupled vibrations for three-phase short-circuit and auto-reclosure fault of 200 MW turbine-generator set are analyzed. The results show that the changed amplitudes of flexural and torsional vibrations relate to the time of short-circuit and auto-reclosure closely. The impulsion caused by auto-reclosure is larger than that of short-circuit. When the fault happened, the former three steps inherence frequencies of torsion are excited, and besides whirl speed frequency some steps inherence frequencies of flexural vibration are also excited. Within the interval from the time of short-circuit to the time of auto-reclosure, torsional torques contain mainly whirl speed frequency and each step inherence frequencies. After the time of auto-reclosure, the frequency components of torsional torque exist all the same, the component of whirl speed frequency disappears.