Vulnerability Assessment of Electric Power Systems Through Identification and Ranking of Vulnerable Areas

Power systems usually support disturbances which may initiate a cascading event that could cause total or partial blackouts. Vulnerability assessment is made in order to establish mechanisms that reduce the risk of blackouts. This paper presents a novel approach for assessing vulnerability of an Electric Power System. For this purpose, several indices, that reflect the health of the system, are calculated and the grid is partitioned in electric areas depending on bus electric coherency. The indices allow assessing four different symptoms of system stress such as voltage instability, poorly-damped power oscillations, frequency deviations outside limits, and overloads. The combination of these indices yields a vulnerability index using a fuzzy inference system. The vulnerability index is an indicator of the health of each electric area. The methodology is tested in the 39 bus New England test system via time domain simulations. The results show that vulnerability begins to develop in a specific region of the system, so its assessment and ranking can be used to coordinate and focus control actions that mitigate the consequences of the disturbances and reduce the risk of cascading events and system blackouts.