Case studies and experiences with Sub-synchronous resonance (SSR) detection technique

This paper will review the Sub-synchronous oscillation phenomena and the interactions between the electrical power system and the mechanical turbine generator system. The paper present captured field data of sub-synchronous and super synchronous resonance at the generator terminals of a nuclear power plant and at a transmission sub-station from a field study during several years. It describes the relationship between sub- and super-synchronous currents and voltages, such as frequencies, dependencies, duration, time constants and magnitudes. From this study, a protection scheme has been devised that easily can be incorporated into a numerical relay using standard protection functions and a numerical multi-purpose filter.