The ability to maintain synchronism when subjected to small disturbances.
Small-Signal Stability
Small-signal stability, as defined in Chapter 2, is the ability of the power system to maintain synchronism when subjected to small disturbances. In this context, a disturbance is considered to be small if the equations that describe the resulting response of the system may be linearized for the purpose of analysis. Instability that may result can be of two forms: (i) steady increase in generator rotor angle due to lack of synchronizing torque, or (ii) rotor oscillations of increasing amplitude due to lack of sufficient damping torque. In today’s practical power systems, the small-signal stability problem is usually one of insufficient damping of system oscillations. Small-signal analysis using linear techniques provides valuable information about the inherent dynamic characteristics of the power system and assists in its design.
Jinning’s Note: The term “small-signal stability” is sometimes used interchangeably with “small-disturbance stability” in the context of power system stability.