Integral square generator angle index for stability assessment

This paper describes an index for judging the severity of transient events in simulation. The integral square generator angle (ISGA) index strongly penalizes diverging generators but also accounts for steady state transfer levels. Previous papers presented the ISGA index to evaluate the effectiveness of discontinuous feedforward controls. Most of this paper analyzes the potential use of the ISGA as a modal performance index and compares it with other modal indices for the step response of a second-order linear system.