Analysis of Time Delay Attacks Against Power Grid Stability

The modern power grid, as a critical national infrastructure, is operated as a cyber-physical system. While the Wide-Area Monitoring, Protection and Control Systems (WAMPCS) in the power grid ensures stable dynamical responses by allowing real-time remote control and collecting measurement over across the power grid, they also expose the power grid to potential cyber-attacks. In this paper, we analyze the effects of Time Delay Attacks (TDAs), which disturb stability of the power grid by simply delaying the transfer of measurement and control demands over the grid's cyber infrastructure. Different from the existing work which simulates TDAs' impacts under specific scenarios, we come up with a generic analytical framework to derive the TDAs' effective conditions. In particular, we propose three concepts of TDA margins, TDA boundary, and TDA surface to define the insecure zones where TDAs are able to destabilize the grid. The proposed concepts and analytical results are exemplified in the context of Load Frequency Control (LFC), but can be generalized to other power control applications.