Identification of Catastrophic Cascading Failures in Protected Power Grids Using Optimal Control

Cascading blackouts of power systems are normally activated by the initial disruptive contingencies under certain conditions. Effective identification of such disruptive contingencies is significant to ensure the reliability and resilience of power systems. This paper focuses on identification of the disruptive contingencies on branches that can result in catastrophic cascading blackouts of power systems. An identification approach based on optimal control is developed to look for the most disruptive contingencies on branches of power networks by treating the disruptive contingencies as control inputs in an optimal control problem. In particular, real-time protective schemes such as generation control and load shedding are incorporated during the sequence of line outages, where such actions are also optimized for preventing the propagation of cascading failures. Moreover, the necessary conditions for determining the most disruptive contingencies on the selected branch are derived by solving a system of nonlinear equations. Extensive simulations are conducted to substantiate the effectiveness and superiority of the proposed identification approach on IMF bus test systems. (C) 2020 American Society of Civil Engineers.