Transient stability margins evaluation based upon probabilistic approach

The paper proposes a new probabilistic approach for deriving the stability margins of an electrical power system, taking into account the stochastic nature of the main problem randomness: the fault clearing time, the reclosing time and the fault type and location. Differently from previous works, the probabilistic approach properly considers also the friction forces which make more difficult the mathematical formulation of the problem. In order to give a measure of the system exploitation with respect its own transient stability, a probabilistic stability index has been adopted in the work. In the last part of the paper, a numerical application is presented in order to show the feasibility and the effectiveness of the proposed methodology.