Probabilistic transient stability assessment using two-point estimate method

With many uncertainties encountered in power system operation, the proper basis for assessing transient stability should be formed in terms of the solution of a stochastic problem. In this paper, two-point estimate method is used to find the maximum relative rotor angles´ probability distribution functions for a given fault with uncertain load demands and clearing time. The low computing time requirement of the two-point estimate method allows online applications, and the use of detailed power systems dynamic model for time-domain simulation which offers high accuracy. The two-point estimate method is integrated in a straightforward manner with the existing transient stability analysis tools. The integrated software facility has potential applications in control rooms to assist the system operator in decision making process based on instability risks. The software system when implemented on a cluster of processors also makes it feasible to re-assess online transient stability for any change in system configuration arising from switching control. The method proposed has been tested on a 39-bus IEEE test system and validated using the Monte Carlo simulation.