Lawrence Berkeley National Laboratory

We propose a computationally efficient method based on nonlinear optimization to identify critical lines, failure of which can cause severe blackouts. Our method computes criticality measure for all lines at a time, as opposed to detecting a single vulnerability, providing a global view of the system. This information on criticality of lines can be used to identify multiple contingencies by selectively exploring multiple combinations of broken lines. The effectiveness of our method is demonstrated on the IEEE 30 and 118 bus systems, where we can very quickly detect the most critical lines in the system and identify severe multiple contingencies.