Data translation and order reduction for turbine-generator models used in network studies

This paper develops suitable procedures for translating high-order networks into conventional stability constants. The approach is computer-oriented and imposes no restriction on the number of equivalent damper windings per axis. Optimum order reduction is used to demonstrate that second-order networks have a bandwidth limited to between 1 and 5 Hz while third-order models may extend this bandwidth beyond 100 Hz. The latter are therefore mandatory for subsynchronous resonance and harmonic studies. In the course of this investigation, the need for a precise definition of the so-called stability constants arises and it is concluded that only a second-order standstill frequency response (SSFR)-based model yields constants that are consistent with the latest, short-circuit test bound, IEEE standard definitions.