Abstract: In a method and system for assessing the stability of an electric power transmission network, where at least one pair of measurements including a first and a second measurement point (P1,P2), each measurement point comprising a voltage and a current phasor, is processed and where a Thévenin impedance (Zt) and a present stability margin (dS(k)) value are computed, a validity indicator (v) is computed which depends on whether there is a difference between the first and second measurement points and whether there is a difference between corresponding estimated first and second load impedances (Za). From all validity indicators (v) associated with all of the at least one pair of measurements a quality indicator (q) is computed that is associated with the Thévenin impedance value (Zt) and with the present stability margin (dS(k)). The invention allows to continuously compute and output a present stability margin (dS(k)) value and to provide a measure (q) of its quality.

Abstract: In a method and system for assessing the stability of an electric power transmission network, where at least one pair of measurements comprising a first and a second measurement point (P1,P2), each measurement point comprising a voltage and a current phasor, is processed and where a Thévenin impedance (Zt) and a present stability margin (dS(k)) value are computed, a validity indicator (v) is computed which depends on whether there is a difference between the first and second measurement points and whether there is a difference between corresponding estimated first and second load impedances (Za). From all validity indicators (v) associated with all of the at least one pair of measurements a quality indicator (q) is computed that is associated with the Thévenin impedance value (Zt) and with the present stability margin (dS(k)). The invention allows to continuously compute and output a present stability margin (dS(k)) value and to provide a measure (q) of its quality.