Haghifam - Tarbiat Modarres University Tehran – Iran
Parsa - Tarbiat Modarres University Tehran – Iran
Seifi - Tarbiat Modarres University Tehran – Iran

over the last three decades, security assessment of power systems has attracted much attention in literature. Crisp thinking of this important subject has caused some problems. The approach described in this paper, proposes a security assessment procedure from reactive power loop viewpoint, based on fuzzy set and probability theories. The security level of the system is calculated in terms of secure set, low secure set, alert set, emergency set, low emergency set and emergency set, with attributed membership values. The approach has been tested on IEEE-RTS (24-bus system) with quite satisfactory results.

Power System Security, Power System States, Fuzzy Probabilistic Security Assessment