Defending against Data Integrity Attacks in Smart Grid: A Deep Reinforcement Learning-Based Approach

State estimation plays a critical role in monitoring and managing operation of smart grid. Nonetheless, recent research efforts demonstrate that data integrity attacks are able to bypass the bad data detection mechanism and make the system operator obtain the misleading states of system, leading to massive economic losses. Particularly, data integrity attacks have become critical threats to the power grid. In this paper, we propose a deep-Q-network detection (DQND) scheme to defend against data integrity attacks in alternating current (AC) power systems. DQND is a deep reinforcement learning scheme, which avoids the problem of curse of dimension that conventional reinforcement learning schemes have. Our strategy in DQND applies a main network and a target network to learn the optimal defending strategy. To improve the learning efficiency, we propose the quantification of observation space and utilize the concept of slide window as well. The experimental evaluation results show that the DQND outperforms the existing deep reinforcement learning-based detection scheme in terms of detection accuracy and rapidity in the IEEE 9, 14, and 30 bus systems.