汽轮发电机组简单轴系模型扭转刚度的简易计算

研究汽轮发电机组扭振问题及次同步谐振/振荡时需使用“简单多质量块-弹簧”模型，其中扭转刚度的准确性十分重要。在已知转动惯量、固有模态频率的前提下，提出一种扭转刚度的简易计算方法，该方法根据已有资料给出扭振振型矩阵的估计值，利用模态向量的正交性求解模态扭转刚度矩阵估计值，反算出扭转刚度；考虑计算结果可能存在偏差，再采用牛顿-拉夫逊方法进行修正。给出沙角C厂1号机组的算例，解决了该机组因为缺失扭转刚度数据导致扭振问题不能详细分析、扭振保护设备不能投运的问题。所提方法计算量小、易于实现，也可以用于扭振保护在实测模态频率之后对轴系模型参数的修正。

Simple calculation for torsional stiffness of steam turbine generator lumped spring mass model

The lumped spring mass model should be used for studying steam turbine generator torsional vibration and subsynchronous resonance/oscillation(SSR/SSO),and it is very important that the torsional stiffness should be calculated accurately. Under the given inertia constants and natural modal frequencies, a simple calculation method of the torsional stiffness is proposed. The estimated eigenvectors of torsional vibration modes are obtained from the collected data. The model torsional stiffness constants are estimated by using the orthogonality of eigenvectors. And then the torsional stiffness could be calculated inversely. Considering the possible error of the results, Newton-Raphson method is used for correction. A case study of Generator Unit 1 in Shajiao Plant C is proposed, which solves the problem that the torsional vibration cannot be analyzed in detail and the torsional stress relay(TSR) cannot be put into operation due to the lack of torsional stiffness data. The proposed method is simple, efficient, and easy to use. It can also be used for the correction of spring mass model parameters for TSR after the natural modal frequencies are measured.