Bahrain - Moshanir Power Consulting Engineers Tehran-Iran
Barkhordar - Moshanir Power Consulting Engineers Tehran-Iran
Hashemi - Moshanir Power Consulting Engineers Tehran-Iran
Saiy - Moshanir Power Consulting Engineers Tehran-Iran

High reliability in operation of complex and integrated networks cause fast recognition of stability/instability qualitative degree required by Energy Management Systems and dispatching centers, in order to avoid and/or decrease instability threat and propose corrective actions for any disturbance occurred in the system. On the other hand, in system planning, we also need a proper tool to select a more secure and stable alternative among different probable cases. One of the methods which provides above objectives to an acceptable degree, is Transient Energy Function (TEF) Method which directly determines network stability. This method is the application of second Lyapunov's Law in power systems. By TEF method, we can do stability studies in near real-time, and also use it as a suitable solution for sensitivity assessments. This method can provide a qualitative judgement on stability, too. Therfore direct methods of transient stability have the potential of meeting some of the needs for Dynamic Security Assessment [1]. In this paper, we present the systematic process for application of energy function method in fast transient stability analysis [2] and after introduction of suitable methods for improvement and simplification of executive calculations, then stability/instability indexes are presented.