The behavior of power systems under oscillatory energy exchange conditions.
Resonance Stability
The resonance, in general, occurs when energy exchange takes place periodically in an oscillatory manner. These oscillations grow in case of insufficient dissipation of energy in the flow path and are manifested (in electrical power systems) in magnification of voltage/current/torque magnitudes. When these magnitudes exceed specified thresholds, it is said that a resonance instability has occurred. The term resonance stability encompasses subsynchronous resonance (SSR), whether it be associated with an electromechanical resonance or an entirely electrical resonance.
The term SSR, as defined in the original publications related to this phenomenon, can manifest in two possible forms: (i) due to a resonance between series compensation and the mechanical torsional frequencies of the turbine-generator shaft, and (ii) due to a resonance between series compensation and the electrical characteristics of the generator. The first of these occurs between the series compensated electrical network and the mechanical modes of torsional oscillations on the turbine-generator shaft, while the second is a purely electrical resonance and termed Induction Generator Effect (IGE).
The resonance stability has been split into these two categories, namely, Torsional Resonance and Electrical Resonance.