Detection of Malicious Command Injection Attacks on Phase Shifter Control in Power Systems

Phase shifters (or phase shifting transformers) are used in power grids to regulate the flow of real power. They are used to prevent overloading of transmission lines and also to regulate cross-network power flows as per contractual obligations. In a smart/automated grid, these phase shift commands are relayed through SCADA networks. As a result, this control is vulnerable to cyber attacks, especially stealthy ones. Malicious phase shift commands can severely overload critical transmission lines, resulting in their disconnection, and also cause financial losses by disrupting cross-network trading. The protection of this control from cyber attacks, though crucial, has not received any attention in literature. This paper is the first which considers such attacks and proposes a method/algorithm to detect them, including the stealthy ones (which beat bad data detection). The proposed algorithm is based on indices that are ratios of branch or node injection currents to the terminal voltages. The effectiveness of these indices (in the context of detection) is validated mathematically. These indices are used to formulate the proposed algorithm which is found to be reliable, computationally light and easy to implement when tested on phase shifters placed in the IEEE 118-bus system. As the proposed algorithm is based on the principles of power system analysis, it is usable under any network technology.