Protecting Control Commands Using Low-Cost EM Sensors in the Smart Grid

Cybersecurity has become an increasing priority for the smart grid. While playing an important role in fault isolation, protective relays are vulnerable candidates for attacks. Compromised protective relays can make wrong control decisions, i.e., tripping a circuit breaker when there is no fault or suppressing a tripping command when there is an actual fault. Such attacks may cause an interruption in operation or, in severe cases, cascading failures. In this paper, we focus on securing control commands associated with protective relays by using low-cost electromagnetic (EM) sensors to infer the current level of a power line and validate control commands from the protective relay of this power line. To account for EM interference from neighboring lines, we develop a deterministic solution that solves linear equations to derive a target power line’s current, and a probabilistic solution that predicts the current value distribution of neighboring power lines and leverages them as well as the target line’s EM sensor measurement to infer the target line’s current. Evaluation results show that our solutions can effectively and quickly detect manipulated commands, thus improving the security of the smart grid.