Prevention of NERC C3 category outages in Idaho power´s network: Risk based methodology and practical application

This paper addresses the development of a risk-based contingency analysis for planning and operating a transmission system. The primary focus of the paper is on assessing power system performance following the consecutive loss of two bulk transmission elements (n-1-1 contingency analysis). The developed approach can be extended to perform the risk-based analysis of other types of contingencies (n-1, n-2, and n-k) used in planning and operation; this approach can use various types of system adjustments as mitigation measures depending on the types and values of post-contingency limit violations. In this paper, we assume generation rescheduling and/or load curtailment are available for mitigation, and these adjustments are given the highest priority. The suggested approach is a further enhancement of the present deterministic approach used by Idaho Power in performing North Electric Reliability Corporation (NERC) compliance studies. Contingency probability, an essential element for risk calculation, was estimated from historical outage data captured and archived by the Idaho Power Generation and Transmission Outage Reporting System (GATOR).