ROBUST OPTIMIZATION OF COMPLEX CYBER-PHYSICAL SYSTEMS

摘要

The incorporation of robust design strategies to increase the insensitivity of system performance in the presence of uncertainty from both internal and external sources into complex system infrastructures can increase system reliability. This paper presents a novel approach to the robust design of complex cyber-physical systems by incorporating a high-level topological optimization strategy for network resilience to reduce the effect of cascading failures. This approach focuses on system robustness after cascading has occurred, and examines performance trade-offs of the resultant (or degraded) system state. In this research, robustness is defined as the resilience to initiating faults, where a robust network has the ability to meet system generation requirements despite propagating network failures. A mathematical model was developed representing a typical power grid network consisting of generation and demand nodes, as well as node connections based on actual topological transmission line relationships. Each node possesses either unique power generation or demand attributes, and various network connection configurations are examined based on system demand requirements. In this model, failure events are initiated by the removal of a single network connection, and remaining loads are redistributed throughout the system. Cascading failure effects are captured when the existing network configuration cannot support the resulting demand load, and transmission line failures propagate until the system reaches a steady state, based on remaining nodes and connections. By understanding network reactions due to cascading failures, as well as performance trade-offs required to mitigate these failures, reliability in power grid systems can be increased.