Online dynamic security control in a large scale power system

Summary form only given. The aim of this paper is to introduce a new methodology, based on dynamic optimization, for assessing preventive control actions to guarantee dynamic security of power systems. In order to mitigate the effect of a contingency, in terms of steady-state or transient violation such as overloads, unacceptable transient voltage dips, system instability, preventive actions are applied as soon as a potentially dangerous violation is detected during a contingency screening. The proposed approach entails the ability to force the system trajectories in an acceptable state space domain under a set of severe but credible contingencies and gives indications about preventive actions when necessary. The approach is sufficiently general to improve the transient behavior of a power system with regard to different objectives such as: to enforce angle stability of the system constraining rotor angle deviations and minimizing the integral of transient kinetic energy across the whole trajectory; and to avoid transient voltage stability using a signal energy based on an integral form of the voltage magnitude at each bus of the system. This methodology consists of an optimization procedure where: the objective function is aimed at minimizing control action efforts; inequality constraints confine the trajectory of the system in a practical domain of the state space ensuring a feasible behavior of the system, power quality, etc.; and equality constraints derive from the discretization of the differential-algebraic equations of the power system sparse representation.