Computation of turbine-generator subsynchronous torsional modes from measured data using the eigensystem realization algorithm

This paper demonstrates the feasibility of using the system identification method known as the eigensystem realization algorithm (ERA) as a means for computing the subsynchronous torsional modes of turbine-generator sets. Measured data obtained during an out-of-phase synchronization test of a large turbine generator are used to perform the modal computation. Both front and rear standard speeds are used. The results are compared with those obtained using more conventional methods.