Abstract
Electrical substations play a crucial role in power grids. A number of international standards, such as IEC 60870 and 61850, have emerged to modernize substations for efficient and timely control. However, owing to insufficient security consideration and implementation, the digitization of a large number of connected substations could dramatically increase the scale of damage on power grids caused by cyber attacks. In this paper, we discuss the practical design, implementation, and deployment of active command mediation defense (A*CMD), a distributed cybersecurity solution to counter attacks injecting malicious remote control commands. A*CMD takes advantage of artificial command-delaying to realize an additional layer of security for each substation in an autonomous, decentralized manner. In particular, for grid operators to make appropriate delay configuration, the procedure to find tolerable delay for a power grid model of interest is formulated and demonstrated with multiple power grid models of different sizes. We further show practical deployment options of A*CMD along with proof-of-concept implementations, whose performance and stability are evaluated with a software-based smart-grid testbed.