MODELING THE IMPACT OF SWITCHYARD LINE FAILURES AND OUTAGES IN THE SONGS SAFETY MONITOR

摘要

The purpose of this paper is to describe the methodology and results of an approach to model the impact of switchyard power line failures/outages and activities in the SONGS Safety Monitor. The Safety Monitor is the configuration risk management monitoring tool used at SONGS for the purpose of the Maintenance Rule (a)(4) assessments. As an enhancement to the Safety Monitor, a study was conducted to determine the risk increase if one or multiple power lines coming into the SONGS switchyard were either removed from service for maintenance or failed. Due to the large number of lines entering the SONGS switchyard and complexity of the switchyard and the grid, the need and possibility of the environmental/test factors (ETFs) approach to address this issue was investigated. The problem was confined to a few cases for consideration of new ETFs for line outage configurations. Each case was assessed to determine its additional loss of offsite power (LOOP) contribution and its frequency was added to the baseline grid LOOP frequency in the Safety Monitor. The line failure and outage data from 1997 to 2007 were reviewed to extract the information required to estimate various line failure frequencies. As a result, two new ETFs were defined, quantified, and incorporated into the Safety Monitor.