Power system transient stability analysis for random initial conditions and parameters

The authors examine the transient ability of a power system model in which the initial conditions and parameters are random variables. This problem is important for analyzing power system security during restorative state operation because the system variables are frequently changing as customer loads are restored. Techniques for a probabilistic assessment of transient stability are described. Due to the computational complexity of these techniques, the authors propose an alternative stability measure that involves estimating the mean and variance of the stability margin. These estimates are developed using an approximate expression for the stability margin and by simulating a single fault-on trajectory initialized from the mean. The use of the method is illustrated on two examples of power systems operating in the restorative state