PROBABILISTIC APPROACH TO TRANSIENT STABILITY EVALUATION

A new probabilistic approach to transient stability evaluation of elec trical power systems is proposed. The method is relevant to planning s tudies, where load level is a major source of uncertainty. The probabi listic nature of both the load demand and the circuit breaker operatin g time is taken into account for the purpose of obtaining an analytica l evaluation of the instability probability. The approach is based upo n the analytical computation of the probability distribution function of the critical clearing time for stability in terms of the load deman d distribution. It allows the expression of the instability probabilit y as an analytical function of all the relevant system parameters. The method is illustrated with reference to a simple (one machine - infin ite bus) system, and the results are compared with those obtained by m eans of statistical (Monte Carlo) simulation. The time requirement of the two methods is comparable, but the proposed analytical approach of fers a remarkable advantage over the Monte Carlo method for a sensitiv ity analysis with respect to the system parameters.