基于贝叶斯序贯博弈模型的智能电网信息物理安全分析

A smart grid is a network which uses communication and information technologies to optimize the transmission and distribution of power from suppliers to consumers. As a kind of cyber-physical system (CPS), a smart grid consists of the network part of data computing and communication and the physical part of all devices. Many security issues arise in both components of the grid, such as injecting bad data, collecting customer privacy information (cyber attacks) and attacking the grid physical devices (physical attacks). In this paper, we study how the system administrator (defender) can determine the type of attack and make optimal protection strategy. We propose a Bayesian sequential game model to defermine the type of attack, and analyze the equilibrium strategy of both game sides according to the sequential game tree. Firstly, we construct a static Bayesian game model between the attacker of an indeterminate type and the defender. We transform the incomplete information game into a complete information game through Harsanyi transformation, and analyze the Bayesian Nash equilibrium to determine the type of attacker. Secondly, we consider the sequential game model between attackers and defenders, which can effectively help defender to make decision in dynamic networks. Through the backward induction, the game tree is analyzed between two types of attackers and defenders, respectively. Then we obtain the equilibrium path of the game tree and make the optimal strategies for both players. It is shown that the defender can determine the type of attacker and make the optimal strategy by the Bayesian sequential game model, which provides a reference for the security research on smart grids.