Optimal Planning and Operation of Hidden Moving Target Defense for Maximal Detection Effectiveness

Moving target defense (MTD) in the power system is a promising defense strategy to detect false data injection (FDI) attacks against state estimation using distributed flexible AC transmission system (D-FACTS) devices. A hidden MTD (HMTD) is a superior MTD method, as it is stealthy to sophisticated attackers. However, the optimal planning and operation of D-FACTS devices that ensure the MTD hiddenness and maximal detection effectiveness are challenging yet unresolved issues. In this paper, we tackle these challenges by first deriving a novel hiddenness operation condition. Then, we propose an analytical sufficient condition on the D-FACTS placement for HMTDs using a graph-theory-based topology analysis. A depth-first-search-based D-FACTS placement algorithm is proposed to guarantee the MTD hiddenness while maximizing the rank of its composite matrix, i.e., an indicator of the MTD effectiveness, and covering all necessary buses. Additionally, we propose DC- and AC-HMTD operation models to determine the setpoints of D-FACTS devices. The optimization-based DC-HMTD model overcomes the drawbacks of the existing HMTD operation. The ACOPF-based HMTD operation model minimizes the generation cost to utilize the economic benefit of D-FACTS devices. Comparative numerical results on the IEEE 14-bus and IEEE 57-bus systems show the efficacy of the proposed planning and operation approaches.