Thermal Vibration Balancing Method for Turbine Generator Rotor. Rotor Vibration Analysis Method due to Thermal Unbalance.

A middle-load thermal power turbine generator frequently exceeds its critical speed, and it must be balanced at the critical speed carefully. Also, it is desirable to thermally balance the generator rotor to reduce the shaft vibration stroke caused by a load change at rated speed. In particular, when the generator capacity exceeds 500MVA, the generator rotor shifts from the secondary mode to the tertiary mode, and the in-phase unbalanced sensitivity increases due to the thermal bending of the shaft and other causes. As a result, thermal balancing is required in addition to conventional mechanical balance. This paper deals with 3 items. The first is the three-dimensional rotor vibration analysis method considered as asymmetry bearing supporting condition and thermal and magnetic unbalanced force. The second is to clarify bearing support condition using the actual rotor vibration response. The last is to explain an agreement between theory and experiment for rotor vibration phenomenon due to an artificial field coil layer short.