Prediction and prevention of cascading outages in Idaho Power network

Modern power systems are designed to withstand n-1 and credible n-2 outages. The ability of a system to survive major disturbances was not comprehensively addressed by system planers. Most large blackouts happening throughout the world involve a sequence of cascading outages that are complex and require adequate methodologies and tools to be addressed properly. Cascading outages expose transmission planners and operation engineers to new challenges, including identifying means to minimize the cascading vulnerability impacts. This paper presents a comprehensive, practical approach to identify and analyze the multiple contingencies that lead to cascading outages in Idaho Power´s network. The primary focus of this paper is to identify the system´s most vulnerable places and double outages that lead to widespread power disruptions and cascading, evaluate their consequences, and identify possible remedial actions to prevent cascading or mitigate its effect. The suggested approach is a further enhancement of the present study approach used by Idaho Power in performing North American Electric Reliability Corporation (NERC) compliance studies. Understanding the effects of cascading on vulnerabilities of Idaho Power´s system is needed to determine when a disruption of service is likely to occur and to take appropriate steps to reduce the associated risk. Understanding cascading outages and being able to predict the associated risks is becoming an integral part of planning and operation studies by Idaho Power. In this paper, a model of the actual Idaho portion of the Western Electricity Coordinating Council (WECC) system was used. The results of the cascading analysis for five base cases are presented.