Integrated treatment of adequacy and security in bulk power system reliability evaluations

Traditionally, bulk power system reliability evaluations have concentrated on the analysis of system adequacy, the ability to supply all loads within performance requirements. The authors focus on extending the scope of reliability evaluations to include a probabilistic assessment of system security, involving considerations of transient stability and the effects of cascading sequences. For each disturbance, first-impact states are defined which depend on the primary effect of the disturbance (static or dynamic problems, or no problem at all). Based on this analysis, a set of probabilistic indices is proposed to assess the security level of the predisturbance state. The possibility and consequences of secondary effects such as cascading are considered, leading to another set of indices to measure load losses due to static and dynamic phenomena. The approach is illustrated in a numerical example