Historical Performance Analysis of Transmission Lines Using Idaho Power Company's Outage Database GTORS

This paper describes a historical performance analysis of transmission lines 46 kilovolts (kV) and above using Idaho Power Company's (IPC) generation and transmission outage recording system (GTORS). The paper is a joint effort by IPC's Reliability and Planning departments to assess the past and future performance of IPC's transmission system and its components. The outage-data statistics of IPC's 46- to 500-kV transmission lines have been analyzed to assess their historical performance and to calculate typical reliability indices to be used in various predictive planning, maintenance, and operation studies. This paper also presents results of identifying the root causes of automatic outages and establishing the relationship between reliability indices and influential factors, such as the voltage level, line length, season, etc. Further, this paper presents the top three leading causes of outages by frequency and duration from 2011 to 2015 and over the 25 years from 1991 to 2015. The importance of use of the presented results by different applications to achieve optimal improvements to the reliability of IPC's system is stressed.