Vulnerability indices for power systems

The purpose of vulnerability assessment is to determine when a disruption of service is likely to occur and to take steps to reduce the associated risk. With the growth of power systems, increases in grid complexity, and the trend toward deregulation, vulnerability assessment is imperative. Accurate vulnerability assessment is especially vital during heavy loading conditions and a vulnerability index is greatly needed to help the operator steer the system to viable conditions. In this paper, two new vulnerability assessment methods are proposed. One is based on the distance of the current operating point from the vulnerability border of the system. The other is an index based on the anticipated loss of load. These two methods are fully applicable to the case of cascading events