State vulnerability assessment against false data injection attacks in AC state estimators

The transformation of the conventional power grid into a smart grid has revolutionised the power industry. However, this has also made the power grid vulnerable to various cyberattacks. This study evaluates the vulnerability of system states, which act as crucial inputs to other essential grid monitoring and control functions, against credible false data injection attacks on nonlinear AC state estimators. Accordingly, two approaches are proposed. The first maximises the yield of the attack, and the second reduces the number of physical meters to be manipulated to launch an attack. This study also develops an attack feasibility index, which can assist in quantifying the feasibility of an false data injection attack while considering various characteristics of a cyberattack. The attack feasibility index also aids in simultaneously comparing the effects of both approaches and assessing the vulnerability of the estimated states. The effectiveness of the proposed methods and the index are established by calculating the state vulnerability of the IEEE 39 bus and IEEE 118 bus test systems.