Computation of static stability margins in power systems using monotonicity

The load-generation margins are calculated for given phase angle safety limits based on the decoupled real power-phase angle (P-θ) load-flow equations. If a load or generator remains within the computed margins, the phase angles are guaranteed to stay within the safety limits, since the method is based on equivalent circuits and monotonicity relations and does not involve any linear approximation. Furthermore, the method allows direct identification of the critical transmission line for the power variation at a given load or generator