Expected angle stability margin

This paper develops a novel concept and computational framework of the expected angle stability margin (EASM) in electrical power systems. This new integrated index provides a common transient (angle) stability characteristic over a set of possible system configurations and contingencies, disturbances and faults, and load demand levels. The EASM expresses a general transient stability “fitness” of the system for a variety of operating conditions. The set of contingencies covered by the index is selected on the basis of their probability, economical, social and system values of the corresponding system configurations. The EASM characteristic can be effectively used to assess the average level of transient stability in power systems. It also evaluates the impact of decision-making in power system reinforcement and expansion planning, and provides an objective for formal optimization procedures in combined stability/reliability studies. A computational scheme for EASM is developed and tested using the IEEE 25-bus test system