435 Rotor-Blade Coupled Vibration Analysis by Measuring Modal Parameters of Actual Rotor

Abstract

Recent turbine-generator set with longer blades for higher output and efficiency, torsional coupled umbrella mode of blades system tends to be nearby the double frequency of electricity system. A quasi-modal technique based on the similar concept of modal synthesis method is proposed, but it is a unique method to provide a visual reduced model. An equivalent mass-spring system is produced for uncoupled umbrella mode and modal parameters are measured in one turbine rotor. The parameters are use to estimate the rotor-blade coupled torsional frequencies of a 700MW turbine-generator set and verified the accuracy of the estimation through a field test.