Dynamic Modeling and Mitigation of Cascading Failures in Power Grids with Interdependent Cyber and Physical Layers

Modeling and prevention of cascading failure in power systems are important topics of research. We propose a dynamic cascading failure model that considers realistic interdependencies between power and communication networks used for system monitoring and control in power grids. In this model, power line outages do not immediately disconnect communication links, whereas communication nodes have battery backup that starts depleting after considerable load shedding in the collocated bus or bus outage. When a communication node's battery is fully depleted, the node disconnects from the cyber layer, potentially reducing the observability and controllability of the power grid. A centralized optimal preventive controller (OPC) to minimize load shedding is proposed for cascade mitigation, which is applied selectively on fully observable and controllable islands. The OPC considers AC power flow equations, multiple hard constraints, and treats overloading of lines as soft constraints. The results of Monte-Carlo simulations on the IEEE 118-bus and the 2,383-bus Polish systems demonstrate that the proposed OPC is effective in mitigating cascading failures. Finally, we demonstrate that our recently proposed Backward Euler method with Predictor-Corrector can reduce the average simulation time by approximately 9-26-folds compared to the Trapezoidal method with acceptable accuracy.