Extended Moving Target Defense for AC State Estimation in Smart Grids

The moving target defense (MTD) that proactively changes series reactance of transmission lines has recently been proposed as an effective defense approach to resist false data injection attacks in smart grids. However, the defense effectiveness analyses of MTD in existing research are mainly focused on linear DC state estimation. To bring the state-of-the-art research to practice, MTD for AC state estimation is investigated in this paper. Specifically, based on a thorough analysis, an extended MTD (EMTD) approach that coordinately changes series reactance and parallel susceptance of lines in smart grids is proposed to improve the traditional MTD. Moreover, the impact of EMTD on electricity market is analyzed. On this basis, the variation of locational marginal price, the variation of active power loss and the cost of devices for executing EMTD are treated as the cost of system defense. Furthermore, to find the trade-off between the defense effectiveness and the cost of EMTD, optimal construction of cost-minimization EMTD topology parameter scheme and defense time interval are also proposed. Finally, extensive simulations are conducted on the standard IEEE test system to demonstrate the effectiveness of the proposed approach.