Practical experience in assessing the effects of extreme contingencies with respect to standards TPL-001-4 and CIP-014-1

This paper presents a comprehensive, practical approach to identify and analyze the effects of extreme contingencies that might lead to widespread power disruptions and cascading. Modern power systems are normally designed to withstand n-1 and credible n-2 outages. The ability of a system to survive extreme contingencies and major disturbances has not been comprehensively addressed by system planners in the past. Extreme outages are a result of either cyber or physical threats. Both types of events expose transmission planners and operation engineers to new challenges, including identifying how to minimize their impact on system vulnerability. The suggested approach is to further enhance the study approach currently used by Idaho Power in performing North American Electric Reliability Corporation (NERC) compliance studies. Understanding the effects of extreme contingencies on vulnerabilities of Idaho Power's system is needed to determine when a disruption of service is likely to occur and how to take appropriate steps to reduce the associated risk. Identification of extreme contingencies using generation reallocation and load shedding for mitigation of their effects are illustrated using an IEEE RTS-96 test system and a model of the actual Idaho portion of the Western Electricity Coordinating Council (WECC) system.