Static Exciter Stabilizing Signals on Large Generators - Mechanical Problems

Torsionalvibrations have been observed on large thermal units with both static exciters, and stabilizing signals based on shaft speed measurement. Studies of transfer functions of round rotor machines and mechanical modes of torsional oscillation of a 500 MW turbo-generator, have led to a solution based on derivation of the stabilizing signal from a speed measurement close to the node of the first torsional mode. New arrangements have been designed and installed on four units now in service.