Investigating voltage collapse scenarios under different contingency conditions are requirement
for proper operation of modern power system. This book deals with developing fast and robust tool to screen the contingencies. Developed algorithm for contingency screening are extended to find physical vulnerability of system. Vulnerability assessment will help with preventive actions to avoid effect of planned or terrorist attack. Mathematical modeling, algorithm developments and solutions have been presented for branch and generator contingencies. Developed algorithm for contingency ranking is fast and efficient and can rank the contingency at the rate of approximately one second for large system like 19140 and can rank in less than 0.13 second per
contingency for small system like 3493 bus case. This book also presents ways to improve the existing continuation method of calculating distance to collapse with proper operation of control device. Work presented here will be great help to industry, researchers and planning authority in studying serious voltage collapse as well as vulnerability problems in the modern power system.