Outage probability evaluation of lines sharing a common corridor

The Western Electricity Coordinating Council (WECC) has established a process for adjusting performance requirements for two lines on a common corridor based on outage probability. Historical outage performance as well as expected future performance from a class of similar facilities may be used in performing the required analysis. The Bonneville Power Administration (BPA) is developing tools to estimate outage performance of facilities on its network by evaluating historical outage behavior of over 15,000 miles of transmission lines over a time period exceeding 15 years. This information will also be helpful in evaluating future transmission alternatives as well as used in day-to-day system screening studies. Also being linked to this effort are robustness standards for improving transmission line and corridor design to reduce common mode outage probability. The analysis will help in developing relationship between facility outage rate and the major influencing factors such as line length, voltage level, number of overhead ground wires and zones. These efforts will help focus planning and operating efforts on those activities that will provide the greatest improvement in reliability.