A new approach to dynamic security assessment using trajectory sensitivities

The transient stability of power systems is investigated using a new analytical tool. Instead of computing the sensitivities of energy margins, trajectory sensitivity functions of the post-fault system with respect to parameters are computed. The goal is to find how sensitive the trajectories of each state are to variations in system parameters. When the system becomes more stressed, the state trajectories become more sensitive to variations in parameters. Thus these trajectory sensitivities can be used as a measure of system security. This concept is illustrated on the IEEE single- and seventeen-machine systems, and it is shown that dynamic sensitivity functions can also be applied to systems of differential-algebraic equations where the TEF method has limitations.