الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
power network is now required to be performed more frequently and by more people in the industry. The conventional methods for studying this behaviour are based on using differential equations to describe the various components of the power network. These methods are now becoming slow and cumbersome. So, the need for a tool to offer qualitative and fast transient analysis have become evident. In recent years, modern methods for studying the stability of the rnultimachine power system (without obtaining time solutions) were introduced. Two of these direct methods are discussed in this thesis which are
1. The energy function.
2. The possibility of parametric resonance in power systems.
In the first part of this thesis, the concept of energy function is implemented in selecting the optimal timing of separation between interconnected power system following large disturbance. The proposed method Is based on the calculated energy function to be stored in each subsystem after sepaation. The value of this energy function, consisting of kinetc energy of generator and potential energy stored in network, is kept constant after fault clearance. If the system damping can be neglected and