Transmission grid vulnerability assessment by eigen-sensitivity and cut-set screening

This paper deals with the assessment of the vulnerability of the transmission grid under extreme contingencies, including a terrorist threat or an exceptional natural disaster. It proposes a two-step screening-and-ranking approach to find the dynamically most disruptive disturbances created by multiple-line outages. In the screening step, critical transmission lines are selected according to the sensitivities of the critical system eigenvalues to the loss of transmission lines, complemented by a topology analysis that searches for the cut-sets in the system leading to islanding. In the ranking step, time-domain simulations are performed for the contingencies given by the combination of lines screened out in the first step in order to determine and classify their actual dynamic impacts. Results obtained from a test system show that the proposed approach is able to screen out most of the critical multiple-line outages in terms of load shedding and transient stability.