Cyber Security Analysis of State Estimators in Electric Power Systems
Abstract:
In this talk, we discuss cyber security of state estimators in Supervisory Control and Data Acquisition (SCADA) systems operating in power grids. Safe and reliable operation of these critical infrastructure systems is a major concern in our society. In current state estimation algorithms there are bad data detection (BDD) schemes to detect random outliers in the measurement data. Such schemes are based on high measurement redundancy. Although such methods may detect a set of very basic cyber-attacks, they may fail in the presence of a more intelligent attacker. We explore the latter by considering scenarios where deception attacks are performed, sending false information to the control center. We introduce a security index for the state estimators which provides a lower bound on the deception attack complexity. The index depends on the physical topology of the power network and the available measurements, and helps the system operator to identify possible sparse data manipulation patterns. This information is then used to strengthen the security by allocating a small number of protected measurement devices. The exact computation of the security index generally requires combinatorial optimization, but we show that it can be accurately estimated also for very large power systems using a minimum cut relaxation.