大型水轮发电机组不对称运行时的参、强联合共振研究

THE STUDY OF PARAMETRIC-FORCED JOINT RESONANCE OF LARGE WATER TURBOGENERATOR UNDER NONSYMMETRICAL RUNNING CONDITION

对某大型水轮发电机转子轴系在发生两相线间突然短路时由电磁力矩引起的扭振进行了研究，探讨了由参数激励、强迫激励以及二者联合作用下轴系扭振共振的规律．首先应用有限元法求得了轴系扭振的前五阶固有频率及振型，接着求得了考虑多磁极（凸极）和振动偏心双重影响下的气隙磁场能量，进而求得了电磁力矩的表达式．应用电机耦联系统的能量法，建立了轴系扭振共振时的一阶近似方程，并对稳态解进行了幅频特性分析，最后计算了轮系的动态应力．研究结果表明，两相线间突然短路时电磁转矩很大，并且其中的100Hz成分与轴系扭振的第二阶固有频率101．182Hz很接近，极剔］起共振，造成破坏，必须设法避免．

The torsional vibration of axle of large water turbogenerator caused by electromagnetic moment under the short circuit between two phase was studied in tHis paPer. We also inquired into the law of torsional resonance excited by parametric excitation and forced excitation. At first,applying the finite element method,we obtained first five order natural frequency and its vibration mode,obtained electromagnetic fleld enegry under condition of multi-magnetic pole(cam pole)and eccentric vibration,obtained the expression of electro-magnetic moment. Secondly applying the enegry method of mechano-electrical coupling system,we set up the first order approximate equation when torslonal resonance occured and carried out magnitude-frequency analysis to the static solution. At last,we calculated dynamic stress of the axle. The results shows that the electro-magnetic moment is very large under the short circuit between two phase and its component of 100Hz nearly equal to the second order natural frequency of 101. 182Hz,so it is easily to cause resonance and destroy,this sltuation must be avoided.