A new trajectory approximation technique for transient stability studies

In many studies involving dynamic models of power systems, fast simulation is needed such as in using direct methods of stability analysis where a number of contingencies have to be simulated in a very short time. In this paper we propose a method which uses piecewise linearization of the nonlinearities combined with trapezoidal integration of the differential equation to approximate the trajectory of a multimachine system with classical model representation. The technique is illustrated for faults on a 3- and 10-machine system and the computational savings are discussed with respect to a fourth-order Runge-Kutta method.